KIN365 Exam 1 Review
KIN365 Exam 1 Review KIN 365
Popular in Applied Biomechanics
verified elite notetaker
Popular in Department
This 63 page Study Guide was uploaded by Jess Snider on Tuesday February 16, 2016. The Study Guide belongs to KIN 365 at University of Alabama - Tuscaloosa taught by Colleen Geary in Spring2015. Since its upload, it has received 90 views.
Reviews for KIN365 Exam 1 Review
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/16/16
KIN365 EXAM REVIEW Exam: 2/18/2016 Muscle & Nerve Phys. ◦ Muscle Types: ◦ Skeletal Muscle: ◦ Smooth ◦ Over 600 responsible for movement of ◦ Cardiac body & joints ◦ Skeletal (the one we cover) ◦ Skeletal muscle roles ◦ Movement: perform opposite joint actions ◦ Protection ◦ Posture & support ◦ Produce body heat: using muscle causes sweating(shivering involuntary ◦ Striated muscle tissue ◦ Voluntary control(somatic) ◦ Individual fibers ◦ Attaches to bone by tendons Skeletal Muscle: structure &function ◦ Tendons: ◦ Three Types of Mysium ◦ Flexible but inelastic cord of fibrous ◦ Epimysium collagen tissue ◦ Surrounds entire muscle & holds it together ◦ No blood supply cannot heal themselves ◦ Outer most layer ◦ Attaches muscle to bone ◦ Perimysium ◦ Allows for movement @ joint ◦ Surrounds group of muscle fibers(fasciculi) ◦ Come from all 3 mysium ◦ Middle layer ◦ Endomysium ◦ Surround individual muscle fibers ◦ Inner most layer ◦ Surrounds: ◦ Sarcoleema: cell or plasma membrane ◦ Sarcoplasm: fluid inside cell or cytoplasm ◦ Muscle cell: contains myofibers ◦ Myofibers made up of myofibrils composed of chain of sarcomeres Sarcomere ◦ Myosin ◦ Sarcomere st ◦ Muscular & thick; makes 1 move ◦ Smallest functional unit of muscle ◦ Contains myosin heads which protrude ◦ Within each myofibril there are 2 type of ◦ Causes binding with actin small protein filaments responsible for muscle action ◦ Forms cross-bridge ◦ Myosin ◦ Interact during muscle action with actin ◦ Actin active sites ◦ Where the striation appearance occurs ◦ Actin ◦ Thin filament ◦ Made up of: ◦ Actin molecules ◦ Troponin ◦ Tropomyosin ◦ during rest stagef actin with myosin ◦ Prevents constant contractions Sliding Filament theory ◦ Cycle of repetitive events that cause the thin, actin filament to slide over the thick, myosin filament to generate tension in the muscle ◦ Res ◦ Excitation-Coupling ◦ Contraction ◦ Recharging ◦ Relaxation ◦ Initiated by action potential ◦ Action potential: ◦ Stimulates the opening of calcium channels ◦ Opening allows for inflow/outflow of calcium which play a hugely important role in muscle contractions Rest ◦ Myosin cross bridge has ATP at tip ◦ ATP binds to myosin & is hydrolyzed by ATPase into ADP & phosphate ◦ Energy released by this process activates myosin head & cocks it into high-energy, extended position ◦ Myosin cross bridge is not attached ◦ Tropomyosin & troponin are blocking active actin binding sites because the calcium ions have not flooded in ◦ Myosin is not attached to actin filaments… preventing binding of the 2 filaments Excitation-Coupling ◦ Calcium ions flood in & attach to troponin actin molecule ◦ Unblocks binding site on action ◦ Results in excitation ◦ Actin filament shifts & changes shape in anticipation of myosin attachment ◦ Myosin heads bind to newly exposed active site on actin filament ◦ Results in Coupling: cross-bridge between myosin & actin formed ◦ Myosin is now attached to actin molecule Contraction ◦ Myosin releases the ADP & phosphate & returns to low energy in position ◦ As ATP is released, myosin pulls thin, actin filament dragged to new location results in Power stroke ◦ Myosin cross bridge changes shape ◦ Shortens sarcomere, drags the Z line to the M line Recharging ◦ A new ATP molecule is put back on the tip of myosin cross-bridge ◦ If this does not happen, the myosin will not let go of action (muscle cramping) ◦ Myosin detaches from actin ◦ If actin binding sites are still available, myosin can bind again with actin Relaxation ◦ When action potentials stop arriving ◦ Calcium releases stops & calcium floods away ◦ Due to motor nerve impulses ◦ Binding sites on actin close, myosin can no longer achieve strong binding ◦ Cross-bridge is prevented ◦ Relaxation of muscle is achieved passively Action Potential ◦ Electrical signal from brain & spinal cord which travels to muscle by way of efferent(motor) nerves signaling the particular motor unit(s) to contract ◦ Initiates the excitation-coupling of myosin & actin during sliding filament theory ◦ Stimulating the voltage- gated calcium channels to open ◦ Stimulus must be strong enough to cause muscle fiber contraction Action Potential Strength ◦ Levels of Strength ◦ Subthreshold: not strong enough to produce action potential in one motor unit ◦ Threshold: strong enough to produce action potential in one motor unit ◦ Submaximal: strong enough to produce action potential in additional motor units ◦ Maximal: strong enough to produce action potential in all motor units of particular muscle ◦ Arrival of single action potential produces a weak brief action of fiber twitch ◦ Not very useful ◦ Producing strong contraction can be accomplished in two ways: ◦ Increase the number of fibers contracting ◦ Increasing frequency of motor unit activation within single fiber ◦ Sending multiple action potentials to muscle fiber Frequency of motor unit ◦ Greater contraction force can be generated by increasing frequency of motor unit activation ◦ Frequency of motor unit activation of single fiber follows: ◦ Latent period: few milliseconds; no change in muscle fiber length ◦ Contraction phase: 40 milliseconds; muscle fiber begins to shorten ◦ Relaxation phase: 50 milliseconds; muscle fiber begins to lengthen back out ◦ Summation: occurs when successive stimuli are provided before the relaxation phase of the 1 twitch st is complete ◦ Subsequent twitches combine with 1 to produce sustained contraction ◦ Equals generation of greater tension than a single contraction would produce initially ◦ As frequency of stimuli increase, the resultant summation increases accordingly producing increasingly greater total muscle tension ◦ Tetanus: occurs if the stimuli are provided at a frequency high enough that no relaxation of the muscle fiber can occur between contractions ◦ Treppe: occurs when multiple maximal stimuli are provided at a low enough frequency to allow complete relaxation between contractions to rested muscle ◦ Slightly greater tension is produced by thestimulus than with the 1 ◦ 3 rgreater stimulus produced even greater tension than the 2 Muscle Contraction ◦ Afferent(sensory) nerves ◦ From muscle to brain ◦ Sends information from muscles to CNS ◦ Efferent(motor) nerves ◦ From brain/spinal cord to muscle ◦ Tell muscles to contract ◦ Somatic Motor Neuron ◦ Nerve cell that processes & transmits information from CNS to muscle ◦ Composed of: ◦ Dendrite ◦ Cell Body ◦ Axon-with myelin sheath ◦ Myelin ◦ Fatty substance wrapped around axon ◦ Speeds up rate of conduction of neurons ◦ Prevents signal decay Motor Neuron/ Nerve Supply ◦ Nerve cells that process & transmits information to directly or indirectly control muscle, including skeletal muscle ◦ Signaled motor neuron may innervate (communicate with) with or many muscle fibers ◦ The motor neuron & all of the muscle fibers which it innervates motor units ◦ Muscle fiber may undergo many action potentials during contraction ◦ Neuromuscular Synapse/Junction ◦ Connects the nervous system of the muscular system ◦ Located at the end of the motor neuron ◦ Allows for the motor nerves to communicate with or innervate muscle fibers Irritability/Excitability ◦ The sensitivity or responsiveness of a muscle to a stimulus-either chemical, electrical, or mechanical ◦ I.e. muscles are considered irritable because can receive & respond to a signal ◦ Without irritability/excitability, muscles wouldn’t fire no movement ◦ Allows for ALL OTHER neuromuscular functions of muscle including contractibility, extensibility, & elasticity Contractility ◦ The ability of muscle to change shape, contract (shorter & thicker), & develop tension or internal force against resistance, IF appropriate stimulus if provided (action potential) ◦ Muscles can develop tension ◦ Property is unique to skeletal muscle ◦ Allows for muscle contractions, tension development, power production which lead to strength & endurance Extensibility ◦ Ability of a muscle to be passively stretched & extended beyond its normal resting length ◦ Can stretch a muscle & all that runs through it ◦ Allows for contractibility & flexibility ◦ Ex: triceps brachii stretched beyond normal resting length when elbow flexors contract to achieve full elbow flexion Elasticity ◦ Ability of a muscle to return to its original or normal resting length following a stretch ◦ Once stretched, a muscle will spring back into original position ◦ Think bubble gum vs. rubber band ◦ Muscle is more like a rubber band ◦ Allows for flexibility Flexibility Endurance ◦ Muscle can stretch through a small or ◦ the ability of the muscle to exert tension over large range of motion time ◦ Dependent on the joint ◦ The longer the tension is exerted, the greater the endurance ◦ Being flexible @ one place, doesn’t mean ◦ Repeated submaximal force development you are flexible elsewhere ◦ Measured over time or by the number of reps can do at certain submaximal amount of force ◦diameter, as training for strength doesuscle fiber ◦ for females no bulking uperred method of training ◦ Uses slow twitch muscle fibers (won’t fatigue quickly) ◦ Factors that affect strength: ◦ Training state of muscle Strength ◦ With both concentric & eccentric strength training, gains in strength over approximately 1 12 weeks appears to be related to neuromuscular adaption, & not increase in cross-sectional area ◦ Neuromuscular adaptation: the improved innervation of the trained muscle, includes: ◦ The component of muscle force that produces torque @ the joint ◦ Increased neural firing rates ◦ Increased excitability ◦ Measured as a function of the collective ◦ Increased levels of motor output from the CNS force-generating capability of a given (more action potentials sent through efferent functional muscle group pathways) ◦ Maximal force can produce @ one period of time ◦ Muscle cross-sectional area ◦ Relates to tension-generating capabilities of muscle with one muscle or muscle group ◦ Measure with 1 rep max=1 rep @ maximal weight ◦ Occurs beyond 1 12 weeks of strength training ◦ Force Arm ◦ Distance between muscle attachment to bone & joint center ◦ Angle of muscle attachment to bone ◦ Maximum when muscle is oriented @ 90˚ angle to the bone with a change in the angle of the orientation in either direction progressively diminishing the amount of force produced Work ???????????????????? ∗ ???????????????????????????????????????????????? Power ???????????????????? = = Time ???????????????? ◦ Factors that affected power: ◦ Muscle power ◦ Muscular strength (force production @ muscle) ◦ =work or force*velocity ◦ Movement speed (velocity) ◦ =work*velocity ◦ Important for anaerobic activities that requir◦ Can also describe power as how long it takes to explosive movements, such as Olympic develop force weight lifting, throwing, jumping, sprinting ◦ Can develop a great deal of force in a short ◦ FT muscle fibers are asset for individuals trainingunt of time= large amount of power for power (FGF) ◦ Muscle Power: force production per unit time ◦ The rate at which work is performed ◦ How quickly can you generate a lot of force ◦ The product of muscular FORCE & the ◦ Two important factors: VELOCITY of muscle shortening ◦ Force of contraction ◦ The rate of force or torque production at joint ◦ Velocity of movement (time) ◦ Power= force*velocity (P=f*v) Power cont. ◦ With relation to concentric contraction: ◦ Force=large ◦ force-=small ◦ Velocity=slow (take a lot of time, time=large) ◦ Velocity=fast (takes a little time, time=small) ◦ Power=force*velocity ◦ Power=force*velocity ◦ =small*small ◦ =large*large ◦ LITTLE POWER ◦ =A WHOLE LOT OF POWER ◦ Slower concentration contractions with a larger ◦ Faster concentration contractions produce less force than any type of slow contractions resistance produce greater force than any fast concentric contractions & slow concentric contractions with less resistance Power Final Statement ◦ Peak power occurs @ ◦ Intermediate level of velocity ◦ Beyond 30% of maximal velocity, power production decrease ◦ Intermediate level of muscle shortening & tension generation ◦ If not stretched beyond 70-80% of resting length, ability to develop contractile tension & exert force is essentially reduced to zero ◦ If stretched beyond 120-130% of resting length, significant decrease in the amount of tension a muscle can develop & amount of force a muscle can exert Injuries ◦ When training for flexibility, strength, endurance, & power, skeletal muscle can exhibit: ◦ Fatigue ◦ Strains ◦ Contusion ◦ Cramps ◦ DOMS ◦ Compartment Syndrome ◦ Cause of Fatigue: Fatigue ◦ Inconclusive, but postulations include: ◦ Reduction in rate of intracellular calcium release & ◦ An exercise-induced reduction in the maximal uptake by sarcoplasmic reticulum ◦ This is a major theory force capacity over time of muscle ◦ The opposite of endurance ◦ Increases in muscle acidity & intracellular potassium levels ◦ The more rapidly a muscle fatigues, the less ◦ Decreases in muscle energy supplies & intracellular endurance it has oxygen ◦ Fatigue may occur in: ◦ Characteristics of Fatigue ◦ The muscle fiber ◦ Reduction of muscle force production capabilities ◦ The motor unit itself (inhibiting ability to generate an action potential=no muscle twitch or contraction) ◦ Reduction of shortening velocity ◦ Prolonged relaxation of motor units between ◦ Variety of factors affect rate of fatigue of muscle recruitment ◦ Type & intensity if exercise ◦ Specific muscle groups involved in exercise ◦ Prolonged twitch duration ◦ Prolonged sarcolemma action potential of ◦ Physical environment in which the activity occurs reduced amplitude ◦ Muscle fiber type & pattern of unit activation Strains ◦ Overstretching of muscle tissue ◦ Magnitude of injury related to size of overload & rate of overloading ◦ Severity & symptoms of strain can be: ◦ Mild ◦ Minimal structural damage ◦ Feelings of tightness or tension in muscle ◦ Moderate ◦ Partial tear in muscle tissue ◦ Symptoms include pain, weakness, loss of function ◦ Severe ◦ Severe tearing of muscle ◦ Functional loss, accompanying hemorrhage, & swelling ◦ Most frequently strained muscle in human body: Hamstrings (lack of flexibility; 2 joint muscle-suffer passive insufficiency) Contusions Cramps ◦ Muscle bruises ◦ Include moderate to sever muscle spasms with proportional levels of ◦ Caused by: compression forces sustained during impacts accompanying pain ◦ Symptoms: hematomas within muscle ◦ Causes: ◦ Etiology is not well understood tissue ◦ Possible factors include: ◦ Can lead to development of much more serious condition called myositis ◦ Electrolyte imbalances ossificans, or calcification within the ◦ Deficiencies in calcium & magnesium muscle ◦ dehydration Compartment DOMS Syndrome ◦ Hemorrhage or edema within a muscle ◦ Delayed Onset Muscle Soreness (DOMS) compartment ◦ Occurs after some period of time followi◦ Caused by: injury or excessive muscular unaccustomed exercise exertion ◦ Arises 24-72 hours after participating in long strenuous bout of exercise (hints name ◦ Pressure increase within the compartment DELAYED, as it is not immediate) causing sever damage to neural & vascular ◦ Caused by: micro tearing of muscle tissue structures within compartments following the ◦ Symptoms include: absence of pressure release ◦ Same kind of histological change that ◦ Characterized by progressive: accompany acute inflammation ◦ Swelling ◦ Pain ◦ Discoloration ◦ Swelling ◦ Diminished distal pulse ◦ Reduced rang of motion ◦ Loss of sensation ◦ Loss of motor function Motor Units ◦ A motor nerve & all that it innervates or communicates with ◦ Depends on ◦ Signals the contraction of muscle fibers if ◦ The number of muscle fibers within each activated motor unit stimulus is adequate for each of the fibers ◦ Action potential ◦ The number of motor units activated ◦ All or none principle: ◦ To produce more force, the main method is to recruit more fibers to contract recruitment ◦ Regardless of number, individual muscle ◦ Recruitment: increase the number of fibers fibers within a given motor unit will either innervated fire & contract maximally or not at all ◦ Main muscular response used to produce greater muscle tension Fiber Composition of Motor Units ◦ Can have motor units with a lot or with a few fibers ◦ Very precise: ◦ Small motor unit ◦ A small number of fibers controlled by one motor unit ◦ Motor units that control eye movement ◦ Less precise: ◦ Large motor unit ◦ A large number of fibers controlled by one motor unit ◦ Quad muscle can have some 500 fibers in motor unit ◦ Motor nerve dictates what type of fiber a motor unit is Muscle Fibers ◦ All muscle contractions/actions are caused by muscle fibers ◦ Two types of fibers: ◦ Slow twitch ◦ Fast twitch Slow Twitch Muscle Fibers ◦ Slow Oxidative(SO) ◦ Build & decrease tension slowly ◦ Fuel source: oxidative phosphorylation ◦ Oxidative phosphorylation creates ATP ◦ Only one type of slow twitch muscle through the electron transport chain ◦ Slow oxidative (SO) ◦ Requires oxygen to create energy ◦ Characteristics ◦ Low strength of contraction ◦ Low anaerobic capacity ◦ Small in size ◦ High capillary density ◦ Highly resistant to fatigue ◦ Use: ◦ Actiivities that are done over a longer period of time but that doesn’t require a great deal of strength ◦ Running a marathon, hiking, walking, swimming long distance Fast Twitch Muscle Fibers • Build & decrease tension quickly • Two types: • Fast Glycolytic(FG) • Fast Oxidative & Glycolytic(FOG) ◦ Fast Oxidative & Glycolytic(FOG) ◦ Fast Glycolytic(FG) ◦ Energy source: hybrid ◦ Fuel source: Glycolysis ◦ Can use energy made fast without oxygen (anaerobic ◦ Glycolysis: energy pathway with 12 steps that gives off a pathway) lot of ATP quickly but also runs out quickly ◦ No oxygen required to create energy ◦ Can use energy made slowly with oxygen(aerobic pathway) ◦ Characteristics: ◦ Characteristics: ◦ High speed & strength of contraction ◦ High speed & strength of contraction ◦ Can use energy made aerobically & anaerobically ◦ High anaerobic capacity ◦ Intermediate sized fibers ◦ Largest of the 3 types of muscle fibers ◦ Low capillary density ◦ High capillary density ◦ Low aerobic capacity ◦ Fatigability varies ◦ More fatigable than SO ◦ Most easily fatigable ◦ Not as fatigable as FG ◦ Uses: ◦ Uses: ◦ Activities that are forceful & quick ◦ Depends on energy source ◦ Sprints, grabbing kid from in front of bus Fiber Composition & Training ◦ Cannot change fiber composition ◦ Fast twitch fibers to slow twitch fibers ◦ Slow twitch fibers to fast twitch fibers ◦ Can change fiber composition of ◦ Fast glycolytic fibers into fast oxidative & glycolytic fibers ◦ Fast oxidative & glycolytic fibers into fast glycolytic fibers ◦ Possible because all with in the fast twitch category ◦ The aerobic capacity & glycogen content of the muscle can be improve with training ◦ Done through specific training ◦ With distance ◦ Produce shift from FG to FOG fibers ◦ With weight training ◦ Produce shift from FOG to FG fibers Selective Recruitment ◦ Neurons tend to recruit smaller fiber types then larger fiber types ◦ Smallest output of force ◦ Slow oxidative (smallest) ◦ Fast oxidative & Glycolytic (slightly larger) ◦ Fast Glycolytic (largest) ◦ Largest output of force Factor Affecting Muscle Tension Development ◦ If summation/tetanus is reached, the force of the muscle contraction of fiber will increase accordingly, because of increased calcium available & a muscle contraction will occur ◦ Two types of muscle contraction ◦ Isometric: no movement (doing a plank) ◦ Isotonic: movement Contractions ◦ When tension is developed in a muscle ◦ Types of Contractions as a result of a stimulus ◦ To initiate or accelerate movement of a body segment ◦ Referred to as muscle action/ joint action ◦ Muscle contractions/actions can be ◦ To slow down or decelerate movement used to cause, control, or prevent joint of body segment movement ◦ To prevent movement of a body segment by external forces ◦ All muscle contractions/actions are either isometric or isotonic Types of Muscle Actions ◦ Isometric Contraction/Action ◦ Isotonic Contractions/Actions ◦ Active tension is developed within muscle ◦ Involve muscle developing active tension but joint angles remain constant to either cause or control joint movement ◦ Static contractions that prevent motion ◦ Dynamic contractions ◦ Significant amount of tension may ◦ The varying degrees of tension in muscles developed in muscle to maintain joint result in joint angles changing angle in relatively static or stable position ◦ Either concentric or eccentric ◦ May be used to prevent a body segment ◦ Concentric—shortening from being moved external forces ◦ Eccentric- lengthening Proprioceptors ◦ Mechanism by which the body is able ◦ Respond to changes in position & to regulate body position & movement acceleration of body segments by responding to stimuli subconsciously ◦ Provide feedback relative to the: & sending that information back to ◦ The position of the body & limbs brain ◦ Movement of joint ◦ These internal receptors are located: ◦ Multiple types of proprioceptors ◦ In the skin ◦ Two stimulated during muscle actions/contractions: ◦ In the inner ear ◦ In & around the joint, muscles, & tendons ◦ Musculotendinous receptors Musculotendinous Receptors ◦ Used in muscular control & coordination ◦ Provide feedback relative to the movements of the joint specifically: ◦ Tension within muscles ◦ Length of muscles ◦ Rate-of-change in length of muscles ◦ Contraction state of muscles ◦ Two Types: ◦ Golgi Tendon Organs (GTO) ◦ Muscle Spindal Golgi Tendon Organs (GTO) ◦ Signals ◦ Located in the tendons ◦ Afferent signals sent up spinal cord in response to ◦ Sensitive to tension development in tendons excessive contraction or passive stretch of tendons ◦ Due primarily to: ◦ Responding efferent signal has two purposes: ◦ Muscle contraction ◦ Inhibition (relaxation) of the contraction of the associate ◦ Passive stretch of tendon muscle (agonist) ◦ associated muscles’ antagoniste opposing muscle, the ◦ Golgi tendon keeps muscle from excessively contracting by ◦ When the Golgi Tendon signals fire, the result is ◦ Inhibiting the motor nerve (protective effect) ◦ Inhibition/relaxation of the agonist (working muscle) ◦ Excitation/contraction of the antagonist (associated ◦ Tension in tendons & GTO increases as muscle muscle) contractions, activating GTO ◦ GTO stretch threshold is reached ◦ Example: ◦ Impulse sent to CNS ◦ A weight lifter attempting an extremely heavy ◦ CNS sends signal to muscle to relax resistance in biceps curllifter reaches a point of ◦ Facilitates activation of antagonist as a protective extreme overload mechanism ◦ GTO activated ◦ Biceps suddenly relaxes/triceps suddenly contract appears as if lifter throwing weight down ◦ Really GTO has caused inhibition of biceps & contraction of triceps ◦ Signals ◦ Afferent signal sent up spinal cord in response to excessive stretch or rapid stretch Muscle Spindal ◦ Efferent sent in response to “stretch” has two purposes ◦ Located in muscle between the fibers ◦ Excitation & contraction of the associated muscle(agonist) ◦ Sensitive to ◦ Inhibition & relaxation of the associated muscles’ antagonist ◦ Degree in muscle strength ◦ Rate if muscle stretch ◦ Antagonist prevented from contracting ◦ When muscle spindal signals fire, the result is ◦ As you stretch a muscle ◦ Stretch of muscle spindals ◦ Contraction of the agonist (working muscle) ◦ Inhibition/relaxation of the antagonist (opposing ◦ Causes exited sensory nerves to send signal up spinal cord muscle) ◦ Examples ◦ CNS sends motor signal to cause a reflexive contraction of the associated ◦ Patellar tendon reflex muscle (agonist contracts) occurs ◦ Sudden tap on patellar tendon causes quick stretch of ◦ Called: Myotatic or Stretch Reflex musculotendinous units of quads ◦ Quick quad stretch activates muscle spindal ◦ Info sent to CNS to quickly contract quads ◦ Cause knee jerk Reciprocal Inhibition ◦ Two things can happen when muscle contracts: ◦ Sensory nerve excites agonist & inhibit agonist ◦ Caused by: Muscle Spindal ◦ Sensory nerves excites antagonist & inhibit agonist ◦ Caused by: Golgi Tendon Organs ◦ Either one occurring is called: Reciprocal Inhibition Fiber Length ◦ Another factor that affects the contraction of the ◦ If a sarcomere is stretched beyond its optimal muscle is the length of the muscle fiber before it is length, force output is virtually zero stimulated ◦ Lack of force production due to actin site blockage by myosin heads preventing new ◦ This length before stimulation & subsequent myosin tetanic tension is called length-tension relationship ◦ Theoretical optimal length of an intact muscle corresponds to muscle resting length ◦ Optimal length corresponds with maximum overlap of thick myosin filament & thin actin filament ◦ The elastic force contributed by elastic ◦ Tension optimized when max. number of active actin components changes optimal length for optimal sites are available force production ◦ If a sarcomere is stretched beyond optimal length, force output declines ◦ Decline occurs because thin filaments pulled away from thick filaments prevent myosin heads from binding Elastic Components ◦ Optimal resting length without series of ◦ Two types of elastic structures found with in components but because of passive tension musclotendon unit developed during motion, elastic components ◦ Parallel elastic component allow for greater tension as the muscle lengthens ◦ Series elastic component or passively stretches ◦ Series Elastic Component ◦ Elastic structures ◦ Passive elasticity derived from: tendons ◦ Non-contractile components of muscle ◦ The elastic component that lies in series (in line) ◦ Lay parallel to or in series with the contractile with the tendons & contractile structures (actin elements within muscle & tendons & myosin) ◦ Non-contractile muscle tissue stretched passively ◦ Provides resistive tension when muscles is ◦ Rather than by muscle contraction passively stretched ◦ Muscle tissues are NOT stretched by muscle contractio◦ If stretched, will spring back (recoil) stretched passively ◦ Tension between them prevent muscle damage that◦ Example: Box jumping could occur from external stretching forces ◦ Eccentric contraction followed by concentric contraction Length-Tension Relationship ◦ Maximal ability of a muscle to develop tension ◦ Generate greatest amount of tension can be & exert force varies depending upon: developed when a muscle is stretched between ◦ The length of the muscle during contraction 70-80% & 120-130% of its resting length ◦ Without elastic component/connective tissue ◦ The relationship between muscle length & muscle tension: ◦ Get most tension out of muscle @ resting length ◦ Shorter muscle=less tension ◦ With elastic component/connective tissue ◦ Generate greatest amount of tension can be ◦ Longer muscle=more tension developed when a muscle is stretched between 120- 130% of its resting level ◦ If not stretched beyond 70-80% of resting length ◦ Ability to develop contractile tension & exert force is essentially reduced to zero ◦ If stretched beyond 120-130% of resting length ◦ Significant decrease in the amount of tension a muscle can develop & amount of force a muscle can exert muscle articulation-biauriculate disadvantage ◦ Active & passive insufficiencies ◦ Active insufficiency ◦ Cannot contract(active) the same amount of ◦ Point reached when muscle becomes shortened to muscle tension or stretch(passive) with the same point it can no longer generate/maintain active amount of flexibility across two joints @ same time tension ◦ ONLY applies to 2 joint muscles ◦ Hamstring muscle ◦ NO insufficient with 1 joint muscle ◦ If shorten/contract across 1 jointhip ◦ Two types: ◦ Cannot keep shortening across other jointknee ◦ Muscle can only shorten/contract so much ◦ Active insufficiency ◦ Passive insufficiency ◦ Passive Insufficiency ◦ State reached with a muscle becomes stretched to point where it can no longer lengthen & allow movement ◦ Hamstring muscle ◦ If lengthen across one jointhip ◦ Cannot keep lengthening across another joint Force-Velocity Relationship ◦ The greater the load against which a ◦ Angle of Pull muscle must contract, the lower the ◦ @ 90˚=100% of muscle force contributes velocity of that contraction will be to movement of the bones ◦ Final player affecting force production ◦ Muscle is strongest @ 90˚ ◦ Muscle is weaker @ either end of 90˚ ◦ Most actions do not require you to hold muscle @ 90˚, so what happens to force production during different types of muscle contractions Muscle Tension • One of two situations occur: • Segment moves • Segment does not move ◦ Dynamic Tension(isotonic contraction) ◦ When the segment moves in the direction or • Two types of tension opposite to the direction of applied muscular • Dynamic tension(isotonic contraction) • Static tension(isometric contraction) tension ◦ Two types ◦ Concentric tension ◦ Static Tension(isometric contraction) ◦ Contraction of a muscle during which the muscle ◦ When a muscle produces tension or force against an shortens & causes movement towards the midline of opposing force or ressitance & the segment of muscle the body does not move ◦ Up movement of push up(tricep), down movement of push ups(bicep) ◦ Only one type: ◦ Eccentric tension ◦ Isometric tension ◦ Muscular contraction during which no discernible ◦ Contraction of muscle during which the muscle segmental movement is taking place lengthens & causes movement away from the midline of the body ◦ Muscles develop tension with no visible change in ◦ Down movement of pushup(tricep), up movement muscle length push up(bicep) ◦ Plank & wall squats, arm wrestling someone Force-Velocity Relationship cont. ◦ Static(isometric) contraction ◦ Concentric(isotonic) contractions ◦ Because static contraction occurs without muscle ◦ Slower speed (velocity) of concentric contraction- movement-velocity is not an issue more force ◦ Static contraction=more force than any ◦ Faster speed (velocity) of concentric contraction- concentric contration least force ◦ Staticce contraction cn develop more force than ◦ Probably due to: even the slowest concentric contraction ◦ High metabolic cost ◦ Due to: ◦ Faster the contraction= fewer cross-bridge ◦ Maximal cross-bridge interaction=max. force interactions(inability of some myosin cross-bridges to output bind with actin sites)= the loss of force production ◦ Myosin cross-bridges, without time constraints, attach freely to active actin sites o Eccentric (isotonic) contraction o Slower eccentric contraction- not as much force o Faster eccentric contraction-more force (up to a certain point) o Eccentric contractions, no matter velocity, can develop more force than ANY velocity concentric contractions & more than static o Due to: low metabolic cost elastic component, increasing # of active cross bridge Summary ◦ Amount of force generates listed from least to greatest: ◦ Faster concentric contraction ◦ Slower concentric contraction ◦ Static/isometic contraction ◦ Slower eccentric contraction ◦ Faster eccentric contraction ◦ Up to a point at which force production levels off Muscle Power ◦ Due to force force-velocity relationship, get maximum amount of force generation @ approx. 30% of maximal contraction velocity ◦ Beyond -30% of maximal velocity, force production decrease with increasing velocity ◦ Slow down amount of time spent on contraction(velocity of shortening) with any amount of force in order to produce greatest amount of power
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'